1. Field of the Invention
The present invention relates to a super-elastic Ti alloy for medical uses. Particularly, the present invention relates to a Ti—Mo—Ga alloy, a Ti—Mo—Al alloy and a Ti—Mo—Ge alloy which exhibit super elastic properties and which are useful for medical applications.
2. Related Art
Recently, many attempts have been made to find medical applications of an alloy with a super elastic property. For example, a Ti—Ni alloy has properties of high strength, excellent abrasion resistance, good corrosion resistance, good biocompatibility and the like, and is used in a variety of fields as an alloy for medical uses.
As an example, a Ti—Ni alloy wire used in an orthodontic appliance has a super-elastic region where constant loading is maintained irrespective of changes in deformation of the wire. Since this wire can impart necessary forces constantly even after teeth are moved by teeth-straightening, it is usable as an orthodontic wire. In addition, such a alloy is also usable in implants for plastic surgery with the full use of its excellent recoverability, and usable for medical catheters, guide wires or the like with the full use of its reasonable formability and stiffness.
Such a Ni—Ti alloy is described in the Japanese Provisional Patent Publication No. 5-295498, which consists of from 49.5 to 51.5% Ni, 1.8% or less Cr and the balance Ti. This alloy is made by casting, hot working and then, repeating annealing and cold working.
In these days, concerns are rising over biomedical materials having a Ni metal which, suspected of causing allergic symptom, may be leached out within the living body. Since a Ni—Ti alloy contains Ni as a principal element, the Ni—Ti alloy may cause anxiety about allergy, and therefore, demands for safer alloys usable in medical applications are growing.
In other words, demands are growing for alloys which contain no element such as Ni that may cause an allergic problem to the living body but have good biocompatibility.